1. Field of the Invention
The present invention relates to obtaining information from an object having a non-flat surface.
2. Description of the Related Art
Surfaces of objects have many different textures. For example, a surface of polished metal has a smooth and glossy texture.
When an object having a non-flat surface is scanned to generate image data, image data will be generated with blur due to the non-flatness. For, example, when a photograph to be scanned is covered with a wrinkled transparent film in a photo album, image data of the photograph will be blurred due to wrinkled portions of the transparent film.
FIG. 9 illustrates an enlarged cross-section of a photograph P and a transparent film F covering the photograph P, and illustrates reflection from the transparent film F in a scanner.
As shown in FIG. 9, there exist intermittent pockets of air between a photograph P and a transparent film F. These pockets cause the surface of the transparent film F to wrinkle.
When a light L1 from a light source impinges on a transparent film F and a photograph P, light is reflected both from the surface of the transparent film F and the surface of the photograph P. The reflected light is guided to an image-input element such as a CCD (Charge Coupled Device) with guiding members (not shown).
In the example of FIG. 9, a specularly reflected light from the region F′ of the transparent film F is guided to the image-input element. Since the intensity of the specularly reflected light is extremely high, the image-input element may be saturated. Accordingly white blurs are generated in the image data. Here, a specularly reflected light means is a light reflected from an object at a reflection angle, which is approximately the same as an incident angle.
The surface of the transparent film F, in particular, is finished to a high level of smoothness when seen microscopically, which means the degree of glossiness is high, thereby raising even further the light intensity level of the specularly reflected light. Often, in photocopiers, the light intensity level of the reflected light from a white reference board is set as a reference level, and any image signals with a light intensity level which exceeds the reference level are treated as image signals signifying white (so-called “shading correction”). Accordingly, the region F′, which corresponds to the reflected light with a high intensity level as described above, appears as several white stripes on the final output image. Thus, an operator is unable to successfully photocopy a photograph as desired.